Synthesis, reactivity and molecular structure of phosphino tetramethyl cyclopentadienyl complex (η5: η1-C5Me4CH2PPh2)Re(CO)2CCDC reference numbers 703987 and 703988. For crystallographic data in CIF or other electronic format see DOI: 10.1039/b820751h

Abstract

The fulvene complex (η⁶-C₅Me₄CH₂)Re(C₆F₅)(CO)₂ reacts at the exocyclic methylene carbon with potassium diphenylphosphide to yield the anionic species [(η⁵-C₅Me₄CH₂PPh₂)Re(C₆F₅)(CO)₂]⁻ (1). Protonation of 1 with HCl at 0 °C produces the hydride complex trans-(η⁵-C₅Me₄CH₂PPh₂)Re(C₆F₅)(H)(CO)₂ (2). Thermolysis of a hexanes solution of 2, under nitrogen atmosphere, produces the chelated complex (η⁵:η¹-C₅Me₄CH₂PPh₂)Re(CO)₂ (3) in good yield. The thermolysis under a CO atmosphere affords a mixture of the complexes (η⁵:η¹-C₅Me₄CH₂PPh₂)Re(CO)₂ (3) and (η⁵-C₅Me₄CH₂PPh₂)Re(CO)₃ (4a). The reaction of 3 with two electron donor ligands yields (η⁵-C₅Me₄CH₂PPh₂)Re(CO)₂(L) (4a, L = CO; 4b, L = PMe₃; 4c, L = ^tBuNC). Complex 3 also reacts with I₂, HBF₄ and MeOTf to yield the cationic compounds trans-[(η⁵:η¹-C₅Me₄CH₂PPh₂)Re(R)(CO)₂]⁺ (5a, R = I; 5b, R = H; 5c, R = Me). Upon treatment with chloroform, the hydride complex 5b converts to the corresponding chloro derivative 5d. The trans stereochemistry for complexes 5 have been assigned on basis of ν(CO) IR intensities and ¹³C-NMR chemical shifts. The reaction of the cationic complexes (5a, 5c) with KI and Me₃NO·2H₂O yields the neutral species cis-(η⁵:η¹-C₅Me₄CH₂PPh₂)Re(I)(R)(CO) (6a, R = I, 6b, R = Me). The molecular structure of 3 and 6a have been determined by X-ray crystallography.